Growing particles in Taylor–Couette turbulence

  • Huisman, Sander (University of Twente)
  • Blaauw, Luuk (University of Twente)
  • Lohse, Detlef (University of Twente)

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For relatively low Reynolds numbers, solid particles inserted in a Taylor–Couette flow with a dissimilar density to the working liquid have been shown to trigger new flow states. In contrast, for the fully turbulent case (Re=O(10^6)) it was found that large solid particles, even for volume fractions up to 6%, have very little effect (within ± ≈ 1%) on the torque required to drive the system. We expect, though, that for large volume fraction, where the particle-particle interactions get stronger, or for even larger volume fractions, where granular jamming occurs, that this will no longer be the case and that the drag will increase. To investigate this, we insert expanding particles made from superabsorbent polymers into the Twente Turbulent Taylor–Couette facility. For fixed Reynolds number of Re=10^6 we will show how the drag evolves over time as the particles absorb water and by this change their size from d≈1.9mm to their final size of ≈7mm, and correspondingly the global volume fraction increases.